Structure and configuration of sacchrides OD sugars can be degraded to the dextrorotatory (+ form of glyceraldehyde. L sugars can be degraded to the levorotatory(-) form of glyceraldehyde. CHO CO2 H一C一OH CHO C02↑ HO-C-H degrade HO C一H degrade CHO CO2t H-C-OH H C- OH H一C一 OH CHO H-( C OH H C一OH H一C一 OH degrade H一C一OH CH2OH CH,OH CH,OH CH,OH D-(+)-glucose D-(-)-arabinose D-(-)-erythrose D-(+)-glyceraldehyde L--编号最大的手性碳决定； 天然存在的糖大多数都是D一型糖 Structure and configuration of sacchrides ⚫D sugars can be degraded to the dextrorotatory (+) form of glyceraldehyde. ⚫L sugars can be degraded to the levorotatory (-) form of glyceraldehyde. D L---编号最大的手性碳决定； 天然存在的糖大多数都是D－型糖